Operation monitoring system for multiflow turbines



Feb. 2, 1965 YUJI KITAGAWA 3,167,952

OPERATION MONITORING SYSTEM FOR MULTIFLOW TURBINES Filed Jan. 31, 1963 BALANCE Figl 21., COMPENSATOR WARNING BELL J9 J9 WARNING LAMP 2 4 22 i A i PRESETTABLE DIFFERENTIAL- 2 t PRESSURE OPERATED CONTROL zb MANoMETRlC PRESSURE-DIFFEREN'ILIAL DETECTING AND INDICATING MEANS United States Patent Ofiice 3,167,952 Patented Feb. .2, 1965 3,167,952 OPERA'IIQN MONITORING SYSTEM FUR MULTIFLGW TURBINES Yuji Kitagawa, Hitachi-sin, Japan, assignor to Kabushiki Kaisha Hitachi Seisaimsho, Cliiyoda-ku, Tokyo-to, lawn, a joint-stock company of Japan Filed Jan. 31, 1963, Ser. No. 255,233 Claims priority, application Japan, Feb. 2, 1962, 37/ 3,313 4 Claims. (Cl. 73-116) This invention relates to an operation-monitoring or surveillance system and, more particularly, to a novel operation monitoring system for preventing flow unbalance in multiflow steam turbines.

With elevation in the temperature and for pressure of the steam for operating turbines, the specific volume of the steam varies greatly from the time at which it enters a steam turbine and the time of its discharge therefrom.

In a high-pressure turbine, the steam passageways, the blade length, and nozzle openings are so constructed as to be small, while in a low-pressure turbine, the steam passageways are required to be extremely large, and the use of relatively long blades is a necessity.

In view of the above conditions, multiflow turbines assemblies, consisting of medium-pressure and low-pressure stages each composed of a plurality of steam turbines of the identical type, are widely used for high-temperature, high-pressure turbine plants of large capacity.

The nature, principle, and details of the present invention will be best understood by reference to the following description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a diagrammatic flow chart indicating a typical example of a steam-turbine combination of the above-stated type; and

FIGURE 2 is a schematic diagram indicating one embodiment of the operation-monitoring system for multiflow steam turbines according to the invention.

Referring first to FIGURE 1, which shows a continuous steam flow system wherein steam is introduced into a high-pressure turbine passes through medium-pressure and low-pressure turbines and is exhausted, high-temperature, high-pressure steam from a boiler (not shown) is conducted by a pipe line 6 to a high-pressure turbine 1 to drive the latter. The steam which has been passed through the high-pressure turbine 1 and has performed work therein, is returned by a pipe 7 to the boiler, where it is reheated by a heater 14 and then conducted into a medium-pressure turbine 2, which consists of two identical turbines in symmetrically opposed arrangement; the steam is introduced into the center and flows outwardly through the two symmetrically opposed turbines, having the form of the so-called opposed two-flow or double-flow type of turbine. The stream which has been passed through the medium-pressure turbine 2 and has performed work therein is introduced through pipes 8 and 9 into low-pressure turbines 3 and 4, respectively, where the steam is expanded to the vacuum of the condenser (not shown). Each of the low-pressure turbines 3 and 4 is of the opposed double-fiow type. Thus, the steam turbine combination illustrated in FIGURE 1 has a form which may be called a quadruple-flow type wherein the exhausted steam is drawn to the condenser through pipes 10, 11, 12, and 13, and the shafts of all of the said turbine units are coupled in alignment on one axis to drive an electric generator 5.

In such a multiflow turbine wherein the steam flow is divided to flow through several turbines, it is requisite, during operation, that the steam flow uniformly through the steam flow paths of all turbines, that is, that the steam flow be prevented from becoming unbalanced.

However, in addition to being created by causes due to the construction of the turbines, unbalanced flow may also be created by such causes as nonuniformity of the flow rates of the steam flowing through the various steam flow paths of the multiflow turbine, the said disturbance occurring when foreign matter, for some reason, adheres to and accumulates on parts of the steam passageways within the turbines, such as nozzles, whereby the effective areas of the flow-path sections at these parts are varied, and the distribution of stage pressure fluctuates. Obviously, it is necessary to fully consider this point at the time of design and to provide means for detecting such unbalance during operation.

As is Well known, if unbalanced flow occurs, the load imposed on one side of the multiflow parts will become large. Moreover, since the turbine combination is designed on the basis of normal operation, the shaft thrusts will become unbalanced. Such effects will be detrimental to the turbine structure and will shorten the serviceable life of the turbine.

It is another object of the present invention to provide a system of simple construction for detecting any occurrence of such unbalanced flow during operation of a multiflow turbine.

In a multifiow turbines, when the steam in the multifiow parts is flowing in a normally correct manner, the steam flow rates and pressures at the same stage of turbines of the same group are the same. That is, if the respective detection points of the turbines are exactly the same, the steam flow rates and pressures at the said detection points should be the same. Accordingly, any pressure difierence at these detection points indicates an unbalanced flow rate, and by detecting this diiierence, detection of unbalanced flow rate can be accomplished. It will be obvious that while it is possible to compare the same pressures by carrying out this pressure detection by making the conditions at the same stage of the various turbines the same as stated above, the detection points need not always be at positions of the same conditions if a certain predetermined relationship between the pressures is utilized, and in this case, the same purpose of detection is achieved with equal facility.

More specifically, it is an object of this invention to provide a monitoring system for multiflow steam turbines which is to be used in conjunction with at least two steam turbines supplied with steam in the same state as stated above, and which comprises pressure detecting means for detecting the pressure at a certain stage of each of the said turbines and means for comparing the pressures so detected by the said pressure-detecting means.

In order to indicate still more fully the nature of the present invention, the following detailed description of one embodiment thereof is presented.

Referring to FIGURE 2, the embodiment of the invention is applied to an opposed double-flow turbine of general type, which consists, essentially, of a rotor 21 coupled to the rotor shaft of an electric generator (not shown) and provided with moving blades 15 which are secured to the rotor, a central steam inlet 18, diaphragms 16 interposed between the moving blades 15 and provided with nozzles through which steam introduced through the inlet 18 is directed outwardly in the axial direction against the moving blades 15 as indicated by the arrows to cause the rotor 21 to rotate, and a casing 17 containing the rotor 21, the diaphragms 16, and other parts.

The monitoring system is arranged and installed in the steam turbine of the above-described construction in the following manner. Pressure detection is accomplished by openings A and B at the extreme ends of two pressure detecting tubes 19, the said openings A and B being disposed respectively in the interiors of the two opposed,

3 double-flow turbine sections, at positions in the respective second stages from the steam inlet, in mutually symmetrical arrangement so as to be under the same conditions in their respective turbine sections. The pressures P and P detected at the openings A and B, respectively,

are transmitted by way of the detecting tubes 19 to a presadapted to light an alarm lamp 21 or sound an alarm hell I 22, via a pressure differential preset control device 23, on a control panel on which various controlling equiptherein Without departing from the spirit and scope of the ment for the turbine-generator are centralized. The pressure comparing device may also be adapted to indicate the pressure diflierence AP directly on the said control panel as is illustrated. It may also operate a compensating device 24 to re-establish the pressure balance.

With the present trend toward even higher steam temperatures and pressures, the number of exhaust flows of multifiow turbines may be expected to increase even further in the future, but by the application of the present invention it is possible to effect constant surveillance for development of unbalanced flow, thereby ensuring solution of problems due to unbalanced flow before they occur. Moreover, the physical apparatus for accomplishing this surveillance is extremely simple in construction and operation. It will be appreciated that, therefore, the present invention accomplishes its objects at low cost and with safe operation.

Although this invention has been described in conjunction with a particular embodiment thereof, it is to be understood that modifications and variations may be made invention, as those skilled in the art will readily understand, and such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

What is claimed is:

1. A monitoring system for the operation of a multiflow turbine assembly including at least two turbines into which are introduced respective flows of an operating pressure medium under the same conditions, said monitoring system comprising a pressure-detecting means for detecting the pressure of the said operating medium at a given stage in each of the said turbines and means for comparing the pressures so detected by the said pressuredetecting means. 7

2. A monitoring system for the operation of a multiflow turbine assembly according to claim 1, wherein the last mentioned means is soconstructed and arranged as to detect and compare the pressures of the said operating medium in the same stage of all of said turbines, and indicate the differential pressure thereof.

3. A monitoring system for the operation of a multifiow turbine combination according to claim 1, wherein the last-mentioned means includes means presettable to a certain limiting value for the differential pressure of the said pressures to give an alarm when the said differential pressure exceedsthe saidlimiting value.

4. A monitoring system for the operation of a multiflow turbine combination according to claim 1, wherein there is further provided in the said pressure-detecting means a pressure-detection compensating device so adapted as to effect compensation for differences in pressures due to differences in the detection measurement positions in the said turbines and thereby to make possible comparison of the said pressures under effectively equal conditions.

- No references cited. 

1. A MONITORING SYSTEM FOR THE OPERATION OF A MULTIFLOW TURBINE ASSEMBLY INCLUDING AT LEAST TWO TURBINES INTO WHICH ARE INTRODUCED RESPECTIVE FLOWS OF AN OPERATING PRESSURE MEDIUM UNDER THE SAME CONDICTIONS, SAID MONITORING SYSTEM COMPRISING A PRESSURE-DETECTING MEANS FOR DETECTING THE PRESSURE OF THE SAID OPERATING MEDIUM AT A GIVEN STAGE IN EACH OF THE SAID TURBINES AND MEANS FOR COMPARING THE PRESSURES SO DETECTED BY THE SAID PRESSUREDETECTING MEANS. 